In computer network systems having data communications equipment, a variety of interfaces are typically necessary to support the users, sub-networks and networks in the system. Multiple pin connectors implementing Single In-Line Memory Modules (SIMMs) on format printed circuit boards have typically been used to support the different interfaces in such networks. Line driver/receivers on the printed circuit boards perform the voltage conversions necessary for network equipment to communicate. Because the various interfaces to be supported have different electrical characteristics, generally only one type of interface can be supported per connector.
Two of the most common types of interfaces known in the art are those used to support data terminal equipment (DTE), and data communications equipment (DCE) such as modems. While there are various vendors for both DTE and DCE interfaces, the connectors on both interfaces have been standardized to ensure that different vendors' equipment can share the same environment without the need for special adapters. Because many systems must support both terminals and communications equipment, it is highly desirable that interface connections be flexible.
There are several methods known in the art which allow a user to alternate between a DCE or DTE interface, depending on the needs of the user. One device known in the art uses a custom cable that connects via straps to an intermediate connector from a standard connector. The custom cable connector is typically adapted to fit either a DTE or a DCE interface connection, but not both, therefore requiring the user to manually alternate between one or the other.
Another method known in the art implements a number of jumper straps, or shorting straps as they are known in the art, as a way to mechanically change connections over from one interface type to another. The shorting straps work in conjunction with associated headers which allow for the shorting strap to physically connect to a standard external interface connector. The shorting straps connect on the printed circuit board between the external interface connector and the line driver/receiver circuitry, and between the line driver/receiver circuitry and the serial communication controllers. The connection to the serial communication controller allows for selection of either the DTE or DCE signal configuration.
The custom cable and shorting strap methods have several drawbacks. First, the cable and the straps are unreliable when exposed to vibration, as there are typically no latches to hold them in place. Also, the straps associated with both methods take up considerable space on a printed circuit board or other medium supporting the standard interface connector. Cost is also a problem, particularly in the case of the shorting straps, where three shorting straps are required to handle a single differential signal.
Also, neither prior art method is particularly flexible in allowing for different interface connections. In the case of the custom cable, a different custom cable will be necessary to support a different interface. Where the shorting straps are concerned, at least fifteen straps must be changed to convert a DCE serial interface port to a DTE serial interface port.
For the above-described interface connector systems, as with most data and communication hardware, there is a premium on increased system flexibility, decreased cost and reduced hardware requirements.
Accordingly, this invention achieves an improved interface connector method wherein a single connector module can support both DTE interface and DCE interface configurations.